1807: Abolition of the Slave Trade Act abolishes slave trading throughout the British Empire. Captains fined £120 per slave transported. Patrols sent to the African coast to arrest slaving vessels. The West Africa Squadron (Royal Navy) is established to suppress slave trading; by 1865, nearly 150,000 people freed by anti-slavery operations.
https://en.wikipedia.org/wiki/Timeline_of_abolition_of_slavery_and_serfdom#1800%E2%80%931829
1807: Abolition of the Slave Trade Act abolishes slave trading throughout the British Empire.
1774: Britain vetos abolitionist laws passed in colonial legislatures in some of the 13 colonies.
Roll back your clock. You're not even in the timeframe of colonial America anymore. You've left the topic altogether.